Proximity sensor technology is used to determine pressure or vacuum levels in containers by measuring lid deflection.
The proximity sensor generates a continuous magnetic field that monitors the distance of the metal lid from the sensor and produces a proportional analog voltage. This continuous signal is digitally sampled and stored in memory. A digital signal processor (DSP) performs multiple algorithms on the stored data to calculate the relative curvature of the lid. The relative curvature value is then compared to user set limits where cans with lid deflection outside these limits are rejected. This technology can be utilized on food cans, beverage cans, glass jars and bottles with pop-button lids.